Pressure relief valve



Feb. 21, 1950 R. A. BROWN PRESSURE RELIEF VALVE 2 Sheets-Sheet l T77 527 07 fz'c am/ raw/z Filed Oct. 5, 1945 Feb. 21, 1950 R. A. BROWN 2,497,860

PRESSURE RELIEF VALVE Filed Oct. 3, 1945 2 Sheets-Sheet 2 Patented Feb. 21, 1950 2.49am raassnae a ain! VALVE alums a. Brown, eel-emcee! assignmto cmcan Bridge & Iron Companma corporation of Application October a, ma'semi No. 019.991

12 Claims. (oi. 137-53) This invention relates'to pressure relief valves,

and more specially to such valves adapted for use on a pressure container. The valve may be used for example. as a pressure relief vent for storage tanks containing gases or volatile liquids.

The new pressure relief valve is of very simple construction, yet has a positive action making it useful on storage tanks for relieving the internal pressure when it exceedsa predetermined value. The valve is adjustable for operation at different pressures and has a snap'action, making its operation very rapid. The valve is especially useful on low pressure tanks such as low pressure spheroids, as it operates rapidly at any predetermined pressure. and this pressure may be quite low.

v The invention the embodiment set out in the accompanying drawings. Of the drawings Fig. l is a plan view of the top of a tank with the pressure relief will be described as related to apparatus attached thereto; Fig. 2 is an elevation in vertical section taken through the pressure relief valve; and Fig. 3 is a fragmentary section similar to Fig. 2 showing the valve in released position.

The pressure relief valveshown in the accom-. panying drawings is mounted on a 'iixed support Ill attached to a hatch ll of a storage tank.

The hatch is connected to the tank by means of a pair of flanges II. On top of the hatch H is located the usual cover l3 and yoke structure I4, pressing downupon the cover. The yoke structure is hingedly attached at one side of brackets II mounted on one side of the hatch l l. The pressure relief apparatus presses against the closed end 16 of the yoke structure l4 to hold the cover normally closed. The yoke structure l4 presses down on the cover i3 through a vertical screw II at the center of the cover. This screw may be regulatedby wheel I! attached at its top end, and thus serves to regulate the distance between the cover i3 and the yoke structure l4. with this construction the cover l3 may be placedover the hatch II, the yoke l4 moved into place thereover, the pressure relief apparatus moved to position to press against the closed end It of the yoke, and the screw i1 may then be turned by the wheel is to press the cover l3 into sealing contact with the hatch ii.

The pressure relief apparatus comprises a wheel I! pressing against the closed endl6 of the yoke -to hold the yoke in place. This wheel is rotatably mounted between the ends of a pair of parallel levers 23 that are attached at their ends toa bracket 2! mounted on the fixed support It.

"The-wheel ends of the levers 23 are mounted on parallel movable bars 22, also attached to the fixed support It. The levers are each formed of two sections 23 hingedly attached together to dorm a continuous lever 20. Pressing against the hinge 24 of the parallel levers 201s a vertical rod 25 located in a cylindrical housing 23. This housing has attached to it at its lower end a chamber 21 containing a flexible diaphragm 23 of leather or the like, to which the rod 25 is attached by means of clamps 23. The diaphragm chamber 21 is in communication at its lower end with the interior of the tank by means of a pipe extending from the bottom of the chamber 7 21 to-the hatch II. The vertical rod 25 is surrounded by a spring 3| located within the cylindrical housing 26. This spring extends between the to of the housing and, a circular plate 32 mounted on the rod 25. The tension of the spring maybe varied by changing. the position of the plate 32. In order to accomplishthis the lower end .'of the rod 25 is threaded and has a nut 33 thereon pressing against the plate 32. In order to provide a .snap action to the pressure relief apparatus, there is provided a pair of substantially parallel springs 34 attached to the lever 20 at .its central hinge 24 and to the housing It. These springs are normally arranged at a small angle below the portion of the lever 23 that'is attached to the fixed support ill. Whenthe tank is in operation with the cover l3 in place on the hatch ii and the yoke structure l4 placed thereover, the wheel i9 is moved into position against the closed end l6 of the yoke structure to hold the cover tightly in place. The

pressure relief apparatus isthen in theposition shown in Fig. 2 with the lever 20 arranged laterally at one side of an imaginary straight line connecting the two ends of the lever. The springs 34 hold the hinged portion 24tightly against the top of the vertical rod 25. This rod then rests on the bottom of the-diaphragm chamber 21. The

spring 3i surrounding the rod 25 has previously been set to a desired tension. As pressure within the tank gradually increases this pressure is come municated through pipe 30 to the bottom of the diaphragm 28. Pressure on the diaphragm tends to push rod 25 upward against the hinge 24 on the lever 20. When the pressure reaches its predetermined value, the slightly bent lever 20 will be pushed past its center line and the springs 34 will cause the lever to snap upward, as shown in Fig. 3, and pull the wheel i9 away from its seat on the end it of the yoke i4. This releases the pressure on the cover l3 and permits the gas to escape from around the cover.

After the pressure within the tank has fallen the apparatus must be reset by hand to its normally closed position. In order to do this a hand lever 35 is provided at the end of the lever section 23 that is mounted on the support to. The

lever 35 andthe section 23 are arranged at right angles to each other with the lever 35 pointed upward.- When resetting the pressure relief apparatus the lever 35 is pushed to the right (Fig.

I claim: 1. A pressure relief vent for a storage tank or the like comprising a casing having an opening,

a movable cover structure for closing said opening, means normally holding the cover shut including lever means fulcrumed at one end to a fixed support and at the other end to a movable support with this latter end pressing against the cover structure, and releasing means communieating with the interior of the casing for moving the movable end of the lever means out of contact with the cover structure when the pressure within the casing reaches a predetermined value, said releasing means including a member actuated by pressure within the chsing to disengage the movable end of the lever means from the cover structure by shortening the effective length of said lever.

2. The relief vent of claim 1 wherein the lever means is formed of two parts hingedly connected together.

the lever is pressing against the cover structure and arranged at the opposite side of said line when the lever means is out of contact with said cover structure.

5. The relief vent of claim 1 wherein the lever means is formed of two parts hingedly'connected together normally arranged laterally at one side of an imaginary straight line connecting the two ends of the lever when the lever means is pressing against the cover structure and arranged at theopposite side of said line when the lever means is out of contact with said cover structure and said lever'means is held in either of the two positions by spring means whereby a snap action is imparted to the lever means on releasing the cover structure.

8. A pressure relief vent for a storage tank or the like comprising a casing having an opening, a movable cover structure for closing said opening, means normally holding the cover shut including a lever means fulcrumed at one end to a fixed support attached to the casing and at the other end to a movable support which is itself hingedly connected to the fixed support, with the lever means pressing against the cover structure at its movable end, said lever means being formed of two parts hingedly connected together normally held laterally at one side of an imaginary straight line connecting the two ends of the lever means when pressing against the cover structure and at 70 2 the opposite side of said line when the lever means is out of contact with said cover structure, spring 4 meansforholdingthe lcvermeansinsaidpcsitions. and releasing means communicating with theinteriorofthecasingformcvingthelever means from its first lateral position to lts'seeond with the lever means having a shorter effective length in its second lateral position.

7. The pressure relief vent of claim 8 wherein the releasing means'aets upon the hinge connecting the two parts of the lever means.

8. The pressure relief vent of claim 6 wherein the releasing means includes a rod means pressing against the hinge connecting the two lever parts and actuated by pressure within the casing.

9. The pressure relief vent of claim 6 wherein the releasing means includes a movable means communicating with the interior of the casing and movable by pressure therein a member attached thereto and pressing against the lever means to move it past said straight line, and an adjustable spring means resisting movement of the movable means. c

10. Thepressure relief vent of claim 6 wherein the releasing means includes a diaphragm communicating with the interior of the casing and movable by pressure therein, a rod attached thereto and pressing against the lever means to move it past said straight line, and an adjustable spring resisting movement of the diaphragm and attached rod.

11. A pressure relief vent for a storage tank or the like comprising a casing having an opening,

. a movable cover structure for closing said opening, a fixed support attached to the casing. a lever means formed of two parts hingedly connected and fulcrumed at one end to the fixed support and at the other end to an arm hingedly attached to the fixed support, said lever means pressing against the cover structure at its movable end and held laterally at one side of an imaginary straight line connecting the two ends of the lever means when pressing against the cover structure and at the opposite side of said line when the lever means is out of contact with the cover structure, spring means attached to the fixed support and to the lever means for holding the lever in said two positions, a diaphragm communicating with the interior of the casing and movable by pressure therein, a rod attached thereto and pressing against the hinge connecting the two parts of the lever when the lever meam is in closed position to move the lever means past said straight line, and an adjustable spring resisting movement of the diaphragm and attached rod.

12. The pressure relief vent of claim 11 wherein the axis of the spring means forms a small angle with the center line of the portion of the lever means that is attached to the fixed support.

RICHARD A. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 109,151 Stewart Nov. 8, 1870 1,668,001 Bolling May 1, 1928 2,231,059 Douglass Feb. 11, 1941 Craig Man-11, 1941 2,297,003 Larson Sept. 29, 1942 Certificate .of Correction Patent No. 2,497,860 7 February 21, 1950 RICHARD A. BROWN It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 33, for the words side of read side to; column 3, lines 39 and 40, for center read centers; line 41, and column 4, lines 46 and 50, after lever insert means; column 3, lines 48 and 49, for two ends read centers of the two fulerums; column 3; line 49, after lever, first occurrence, insert means;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed 13th day of June, A. D. 1950.

! Tr-Ioms F. MURPHY, v

Assistant Oommissioner of Patents. 

